3/8 NC Orifice Screw for general use. Multiple sizes available, select them from the drop down list of values. Typically used for internal blank adaption of M1 Garand, M1 Carbine and other .30 caliber weapons. This screw is used in our 1919A4 and 1919A6 BFA kits. This screw does not fit our M1 Garand Blank Adapter.